Spaceflight Insider

Arianespace successfully launches two Galileo navigation satellites

Tomasz Nowakowski

September 10th, 2015

Archive Image. Photo Credit: S. Corvaja / European Space Agency

Two European navigation satellites, Galileo 9 and 10, named Alba and Oriana, are now on their way to a circular medium-Earth orbit (MEO) after being successfully launched by a Russian Soyuz ST-B rocket. The dual launch was conducted by Arianespace at 10:08 p.m. EDT on Thursday, Sept. 10 (02:08 GMT on Sept. 11), from the Soyuz Launch Complex (ELS) in Sinnamary, French Guiana.

The mission, designated Flight VS12, will increase the number of satellites in the Galileo global navigation system to 10. The two satellites will reside at an orbital altitude of 14,615 miles (23,521 km) and an inclination of 57.4 degrees toward the Equator. The Soyuz launch vehicle carried a total payload of some 1.6 metric tons, including the 1.43 metric tons of the two spacecraft.

The Galileo system is meant to be similar to the U.S. GPS and Russian GLONASS navigation systems. (Click to enlarge.) Photo Credit: Arianespace

If everything continues to go according to Europe’s schedule, two more Galileo satellites are planned to be launched by year’s end.

At T–0, the Soyuz launcher ignited its main engines and lifted off, turning northeast from the French Guiana spaceport. About 118 seconds after the launch, the four boosters of the rocket’s first stage were jettisoned. It was followed by the jettisoning of the fairing, approximately 102 seconds later. Next, nearly 5 minutes into the flight, the second stage separated from the launch vehicle.

The ascent to space lasted just slightly more than nine minutes, after which the rocket’s Fregat upper stage fired twice to place the satellites into their release orbit.

The Galileo satellites will separate from the Soyuz launch vehicle 3 hours and 48 minutes after liftoff. They will be released in opposite directions by their dispenser once they reach their designated orbit. After the successful orbital injection, the Fregat upper stage will be deactivated and the three lower stages and payload fairing will then fall back into the sea.

After their deployment, the two satellites will operate at MEO in Galileo’s Orbital Plane A – one of three orbital planes being populated by the Galileo fleet.

A team of mission control experts in Darmstadt, Germany, are working around the clock to bring the duo through their critical first days in space.

The launch starts the 10-day operations phase, during which the team will work 24 hours a day to oversee steps to prepare the satellites for handover to the Galileo Control Centre in Oberpfaffenhofen, Germany, for routine operations, and European Space Agency’s (ESA) Redu Centre in Belgium, for detailed payload testing.

At this point, the In-Orbit Test (IOT) phase commences in which the accuracy and stability of the satellites’ onboard clocks are measured, as well as the quality of the navigation signals is assessed.

The IOT ground station is equipped with an L-band receive-only antenna to receive satellite navigation signals, a C-band transmit antenna to send navigation messages to the satellite payload, and a UHF transmit antenna for transmitting simulated search and rescue signals to the satellite.

Galileo is a European project that is currently creating a new global satellite navigation system, carried out on behalf of the European Commission, under a contract with ESA. Under civilian control, Galileo is planned to deliver high-precision positioning services. The network is designed for interoperability with the U.S.’ GPS and Russian GLONASS global positioning systems.

The current Galileo 9 and 10 FOC (Full Operational Capacity) satellites are planned to be operational for more than 12 years, They were built by Bremen-based (Germany) OHB System as the prime contractor, with their navigation elements provided by Surrey Satellite Technology Ltd., UK, a 99 percent-owned subsidiary of Airbus Defence and Space. The two spacecraft on Flight VS12 will be the fifth and sixth OHB-built satellites. Each satellite is named after one of the children who won a painting competition organized by the European Commission in 2011.

The Galileo satellites are equipped with two passive hydrogen maser atomic clocks; two rubidium atomic clocks; a clock monitoring and control unit; one navigation signal generator unit; L-band antenna for navigation signal transmission; C-band antenna for uplink signal detection; two S-band antennas for telemetry and telecommand as well as one search and rescue antenna.

Europe plans for a constellation of some 30 Galileo satellites. Image Credit: EU

The VS12 mission got its official start with the arrival of the satellites in French Guiana on July 24 of this year. At the end of August, the spacecraft were fueled and attached to the dispenser that holds them in place during ascent. They were then attached to the Fregat upper stage and cocooned within Soyuz’s fairing.

This flight marks the first use of a new fueling facility at the European spaceport. Called FCube, short for Fregat Fueling Facility, the building was constructed to pump hydrazine and nitrogen tetroxide propellants into the Fregat upper stage.

The FCube was developed to reduce the time required to “top off” Fregat upper stages, which takes several weeks as part of Soyuz launch campaigns.

FCube also frees up another Spaceport facility previously used for Fregat upper stage fueling operations – the Spaceport’s S3 building.

This makes the S3 facility more available for the processing of customer spacecraft to be lofted by the various members of Arianespace’s launch vehicle family.

The FCube facility consists of two structures: one building that serves as the remote control center and includes a zone where fueling operators are suited up in their protective clothing; and the other with the Fregat fueling hall, along with the storage for propellant and gases, and areas to hold support and spare equipment.

The Soyuz rocket was rolled out onto the launch zone on Monday, Sept. 7, in the Spaceport’s northwestern sector near the city of Sinnamary. This was followed by the launch vehicle being raised into the vertical position and suspension over the launch pad.

After the mobile gantry was moved in to protect the booster, the mission’s Fregat upper stage, the two dispenser-mounted Galileo satellites, and payload fairing were hoisted and mated atop the Soyuz.

The Launch Readiness Review (LRR) was conducted on Wednesday, Sept. 9, to authorize the start of operations for the final countdown.

The version of Soyuz currently offered by Arianespace is a four-stage launch vehicle which includes the following: four boosters (first stage), a central core (second stage), third stage, and a restartable Fregat upper stage (fourth stage). It also includes a payload adapter/dispenser and fairing.

The booster’s RD-107A engines are fueled by kerosene with liquid oxygen as the oxidizer; the same propellants are used on each of the lower three stages.

The central core is similar in construction to the four boosters, with a special shape to accommodate the boosters. A stiffening ring is located at the interface between the boosters and the core. This stage is fitted with an RD-108A engine, also comprising four combustion chambers and four nozzles.

The third stage uses an RD-0124 engine in the ST-B version. The third stage engine’s thrust enables the stage to separate directly from the central core.

The Fregat upper stage is an autonomous and flexible stage that is designed to operate as an orbital vehicle. It extends the capability of the Soyuz launcher, now covering a full range of orbits. To ensure high reliability for the Fregat stage from the outset, various flight-proven subsystems and components from previous spacecraft and rockets are used. The upper stage consists of six spherical tanks (four for propellants, two for avionics) arranged in a circle and welded together.

The first Galileo satellites were launched atop a Soyuz rocket on Oct. 21, 2011. Prior to today’s launch, the previous satellites to be sent aloft (7 and 8) in the series were successfully orbited on March 27, 2015. Today’s flight marked the 12th Soyuz launch from the Guiana Space Center and Arianespace’s eighth mission of 12 planned for 2015.

Tomasz Nowakowski is the owner of Astro Watch, one of the premier astronomy and science-related blogs on the internet. Nowakowski reached out to SpaceFlight Insider in an effort to have the two space-related websites collaborate. Nowakowski’s generous offer was gratefully received with the two organizations now working to better relay important developments as they pertain to space exploration.